Intratypic serodifferentiation of polioviruses

The intratypic serodifferentiation technique described by Wecker has been applied to the antigenic analysis of a number of attenuated and virulent strains within the same poliovirus type. By comparison of plaque inhibition produced by strain-specific immune sera, different pools of the same attenuated strain were found to be serologically identical, whereas other attenuated and virulent viruses could be distinguished antigenically from one another. The antigenic character of viruses passed in tissue culture was relatively stable, even when other markers changed considerably. After passage through laboratory animals or in the human intestine, however, some strains were stable while others were not.The applications of this test to studies of vaccination with living attenuated polioviruses are illustrated.